1. Field of the Invention
The present invention relates to a charging circuit and, more particularly, to a charging device for charging various kinds of batteries having different charging voltages and capacities.
2. Description of the Related Art
With the development of battery technology, various charging batteries, such as first cell, secondary cell, fuel cell, and physical cell, are being produced. As many kinds of batteries of user demanded capacities become popular, they are widely used in the form a cell or pack in electronic appliances. However, even for the same family of batteries, their charging voltages vary. For instance, the lithium-ion battery, widely used in communications apparatuses, has roughly three kinds with different charging voltages. The graphite series and non-graphitizable carbon series have the maximum 8.4V of charging voltage, the coke series having 8.2V. Even the same lithium-ion battery has different charging voltages in accordance with internal density and internal material components. Since the charging voltage and capacity varies with batteries, different charging devices are needed.
As mentioned above, charging devices are required for the respective charging voltages and capacities, and this makes the user's selection range narrow. In other words, what one kind of charging device can charge is limited to only one battery of a fixed capacity determined in the design of the charging device.